/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: VoidType.java,v 1.2.4.1 2005/09/05 11:45:26 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler.util;

import com.sun.org.apache.bcel.internal.generic.Instruction;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.PUSH;
import com.sun.org.apache.xalan.internal.xsltc.compiler.Constants;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 */
public final class VoidType extends Type {

  protected VoidType() {
  }

  public String toString() {
    return "void";
  }

  public boolean identicalTo(Type other) {
    return this == other;
  }

  public String toSignature() {
    return "V";
  }

  public com.sun.org.apache.bcel.internal.generic.Type toJCType() {
    return null;    // should never be called
  }

  public Instruction POP() {
    return NOP;
  }

  /**
   * Translates a void into an object of internal type <code>type</code>.
   * This translation is needed when calling external functions
   * that return void.
   *
   * @see com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
   */
  public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
      Type type) {
    if (type == Type.String) {
      translateTo(classGen, methodGen, (StringType) type);
    } else {
      ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
          toString(), type.toString());
      classGen.getParser().reportError(Constants.FATAL, err);
    }
  }

  /**
   * Translates a void into a string by pushing the empty string ''.
   *
   * @see com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
   */
  public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
      StringType type) {
    final InstructionList il = methodGen.getInstructionList();
    il.append(new PUSH(classGen.getConstantPool(), ""));
  }

  /**
   * Translates an external (primitive) Java type into a void.
   * Only an external "void" can be converted to this class.
   */
  public void translateFrom(ClassGenerator classGen, MethodGenerator methodGen,
      Class clazz) {
    if (!clazz.getName().equals("void")) {
      ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
          toString(), clazz.getName());
      classGen.getParser().reportError(Constants.FATAL, err);
    }
  }
}
